This invention relates to an exhaust gas sampler for an internal combustion engine and particularly a marine outboard propulsion engine.
In many instances, it is desirable to sample the exhaust gases from one or more cylinders of an internal combustion engine. This sampling may be done continuously during engine running for control purposes or may be done periodically to determine the condition of the engine.
The way this sample is normally taken is that there is a port in a portion of the exhaust system through which a sampling tube may be extended so as to collect the combustion products upon discharge from the cylinder. Although this concept is quite effective, in some specific applications there can be specific problems.
For example, with marine propulsion engines it is the normal practice to cool the engine by circulating water through the cooling jacket from the body of water in which the watercraft is operating. The water is then returned back to the body of water in which the watercraft is operating. Normally, this is done by discharging the cooling water from the engine into the exhaust system. In this way, the cooling water can be conveniently disposed of. In addition, the addition of the cooling water to the exhaust system provides added silencing and cooling effects.
However, where this is done it has been previously the practice to have the sampling pickup location located in such an area that it could collect water along with the exhaust gases. In addition, the sampling tube may frequently pass through the engine cooling jacket and, hence, the exhaust gases will be cooled and some exhaust gas constituents may condense out from the exhaust gases. Either of these results will result in incorrect sample or reading of the exhaust gases.
It is, therefore, a principal object of this invention to provide an improved exhaust gas sampling device for a marine propulsion engine.
It is further object of this invention to provide an exhaust gas sampling arrangement for a marine propulsion engine wherein the exhaust gas samples are collected at a point well upstream of where the cooling water is introduced into the exhaust system.
It is a still further object of this invention to provide an improved exhaust gas sampling arrangement for a marine propulsion engine wherein the sampling tube does not extend through any cooling jacket of the engine so that the exhaust gases sampled will not be cooled.